


NSFW Undertale One-shots

by UnparalleledAngel



Category: Undertale (Video Game)
Genre: Drunk Sex, F/M, Frottage, Multi, Overstimulation, Roleplay, Spanking, messy sex
Language: English
Status: Completed
Published: 2018-11-06
Updated: 2018-11-22
Packaged: 2019-08-19 22:38:26
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 4,432
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16543637
Author URL: https://archiveofourown.org/users/UnparalleledAngel/pseuds/UnparalleledAngel
Summary: A collection of Undertale one-shot requests I took on my blog mtt-metal-boner. Decided to share them here too!





	1. Mettaton x Reader - Roleplay

Mettaton didn’t know the meaning of “casual”. Nothing he ever did was casual, he went by every moment of every day dramatising everything he got his hands on. He strived to make every second he lived and breathed exciting, turning it into some mass production of his own making.

And, being his girlfriend, you were quickly swept up in the adventure that was Mettaton’s life.

That was why, when he had you suddenly visit him at his set, only to stow you away in someone’s empty office, gave you a ‘naughty schoolgirl’ get-up to wear, and hurried off to get himself ‘ready’, you could hardly be surprised. You were beginning to get used to his odd spontaneity.

The outfit was made up of a white short-sleeved shirt, cropped blazer, black and red tie,  _extremely_  short skirt that barely covered your ass and white stockings. Despite its unorthodox nature, you couldn’t help but notice how every item of clothing was perfectly sized just for you, making you sure that this hadn’t been just a spur of the moment idea Mettaton had put together. He’d been planning to get you in this for a while…

It took you a mere five minutes of waiting (which you were glad of because you were becoming increasingly anxious about someone entering the room that wasn’t your ridiculous boyfriend and seeing you in your even more ridiculous outfit) for Mettaton to turn up, slipping through the door in a red velvet suit and black thick-rimmed glasses perched upon his prominent nose.

“Ah, y/n, I’ve been waiting for you!” he said, smirking as he looked you up and down, taking in your body in that particularly revealing outfit he’d got you to put on, obviously pleased with how it turned out.

“What are you talking about- I’ve been waiting for you!” you said, a little exasperated at his behaviour. Why didn’t he ever explain anything he did?

“You were called into my office because…” he put a finger to his chin, looking up as though he were trying to recall something, “You were caught breaking the uniform code.”

You rolled your eyes, feeling your cheeks flare up involuntarily as you said, “So we’re just gonna jump straight into this?”

Mettaton got close then, backing you into the desk that was just behind you and leant down to your ear. “Darling,” he whispered in that elegantly low rumbling tone, making you shiver, “We have thirty minutes before the director gets here and wants his office back, I saw the opportunity and took it. I’ve been wanting to get you in this outfit for weeks now…”

“Why didn’t you just…” You looked up at him, into those pleading eyes and found yourself struggling to find words, “You know… bring the outfit home with you and I could have worn it there?”

He silenced you with a finger across your lips, “Because there’s no fun in doing it at home, beautiful. Now– where were we? Ah yes, the uniform!” He brought his hands down to your chest and you felt your breathing hitch, watching as he loosened your tie and popped open a few buttons of your shirt until your black, lacy bra was showing. “There, perfect! Remember to follow ‘Mettaton’s School For Whores and Dirty Sluts’ code of conduct more closely from now on.”

You couldn’t help but giggle at his made up name, quickly covering your mouth to try and stay in character for him.

Mettaton however, took the laugh in his stride, grabbing onto the little opportunity to further his improvisation. He turned stern suddenly, turning your face by the jaw to look up at him. “Laughing at me, are you? Do you think this school is nothing but a joke? That the mandatory bra-showing rule is laughable? I suppose I’ll just have to give you a suitable… punishment.” He let the word roll over his tongue as though tasting it. “Bend over, you  _naughty girl_.”

You felt a wave of excitement wash across your body as you leant over the desk, knowing exactly what Mettaton had in store for you. With deliberate slowness, Mettaton lifted your skirt over your ass like he was unwrapping a delicate gift. You heard him hum with delight and take a moment to appreciate his view before a metallic hand was felt, kneading your behind.

“Didn’t think to take off your underwear for this, hmm?” he asked, before realising he was breaking out of character and staged a cough. “Prepare yourself for your punishment, darling,” he reminded you. 

With a precise slap, that same fondling hand was brought down sharply onto your cheeks, sending out a cracking noise into the air. You groaned, wiggling your ass at him in an almost taunting motion until he gave you a swift second spank that made you choke on your hubris.

“Now now,” he said, voice as cold as frost-bitten metal, “We’re not enjoying our punishment, are we?” He gave you another slap that made your legs shake.

“No no, not at all enjoying it!” you moaned, all four of your cheeks burning from his actions, “Not at all!”

“Good,” he replied, giving you another slap that made your toes curl, “We wouldn’t want you to get the wrong idea. I’m entirely professional, you know.” You felt him fondle your underwear then, sticking his fingers under the hem. “Which is why I think these panties should come down. You might enjoy your punishment a little less when there’s no fabric protecting your perky ass, darling.”

You nodded, shivering as you felt the cold air of the room hit your behind, your underwear being pulled over your ass and left hanging around your knees. Mettaton didn’t stop to admire the view this time, abruptly returning to his relentless spanking, one cheek and then the next until your ass was beaming and your moans were growing intense.

He hummed in thought after a short while, smoothing the palm of his hand over your now reddened ass as though in awe. “Now I’ll have to make sure my punishment has gotten through to you,” he said, making you wonder what on earth he meant before you felt his warm fingers slip between your legs, rubbing your pussy with expert control. Your knees almost buckled as his index finger rounded your clit. “Ha! No impact at all, it seems,” he said, taking his hand out again and wiping it on your thigh, “You’re  _wet_. Disgustingly so. Didn’t I tell you not to enjoy my punishment?”

“Y-yes, sir,” you moaned, just wishing he’d keep touching you.

“I’ll have to come up with another method to make you rethink your ways,” he said then, tapping your ass lightly and telling you to get up.

You did so, completely forgetting about the sting of your asscheeks for all the anticipation Mettaton was putting you through. You let your underwear fall down to your ankles and kicked them off. As soon as you did, Mettaton pressed you back down onto the desk and laid you down on your back, bringing his hands up to your buttoned shirt and ripping it open down the front. The look of lust was undeniable in his eyes.

He took his glasses off of his nose and threw them across the room suddenly. “I’ve just thought of the perfect way,” he announced as he spread your legs and lifted your skirt up at the front. “It’s sure to put you on the straight and narrow.” He reached down placed his hands on his belt, undoing it just enough to unzip his pants and take out his eager cock. “You’re going to make me feel good.”

“Do I get extra credit?” you asked, smirking as you did so, knowing full-well you were about to get the imaginary cane.

“This is a punishment, y/n,” he said sternly as he lined himself up with your entrance, finding himself slipping inside with ease from how wet you were.

You groaned as you felt him stretch you deliciously, leaning over your body on the desk, so close that his lips were near enough to kiss. But, of course, kissing would be extremely unprofessional in this situation.

“I-if it’s a punishment,” you began as he started thrusting, quickly finding himself a fast-paced rhythm, “Then why does i-it feel so  _good_?”

Mettaton moaned, breaking character instantly as he began stimulating himself. “God, it really does feel good, doesn’t it?” he huffed, his hot breath reaching your gasping lips, “ _So_  good.”

You clung to him like wet paper, legs around his hips, arms around his chest, pulling him closer and desperately keeping him there.

Mettaton’s hips fucked you with a steady but relentless rhythm, never stopping for a break, not needing to with all of his incredible stamina. He kept going and going until he seemed to get overwhelmed by the sensation, burying his head into the space between your shoulder and neck. Somewhere in the midst of his actions, you felt his pants fall down from his hips to the floor, leaving his shapely bare ass out in the open for you to grasp at and squeeze whilst he fucked you into the desk.

“I might have to break the rules more often!” you panted, “I-if this is the punishment!”

“O-oh God, darling. I hope you do. You’re just such a bad girl I– oh God!”

It wasn’t long before you were howling out his name, repeating it like the noise would help steady your spinning mind. Had you had any other care in the world at that moment, you’d have worried someone outside would hear your screeches and try to come to your rescue. But as it was, you didn’t care at all what happened as long as Mettaton kept going and pushed you over the edge.

Coming along quicker than you expected, out of nowhere like being hit by a truck on a seemingly empty street, you came. Hard and fast, you clenched around him, whining as his never-ending thrusts pushed you further and further into your orgasm and out onto the other side. Before you could get particularly overstimulated, you felt Mettaton shudder and grunt into your neck, his movements slowing considerably as he rode out his own orgasm, enjoying every last second of it.

Once he was completely satisfied, he leant up on his hands and slipped out of you, looking incredibly flustered in comparison to the character he was playing before. Despite this, however, he still managed to make a smirking remark, “I told you it would be more exciting than at home.”

You rolled your eyes and grabbed his tie, pulling his smarmy face down onto your lips, taking that kiss you’d been missing out on. He made a noise of shock before melting into it, stroking your hair with his clean hand.

You two stayed there for a moment, enjoying the floaty feeling of being recently satisfied until Mettaton pulled back, a wild look in his eyes.

He glanced at the clock on the wall above your head and looked even wilder. “We have two minutes to get out of here and–” he was cut off by the sound of the door rattling behind him and he spun around, making your heart pound. “Oh fuck… I’m definitely getting punished for this.”


	2. Papyrus/Reader - Lazy Sex

Papyrus had been training hard recently.

Even harder than usual. When he wasn’t sparring with Undyne, he was down at the gym, ‘pumping up his muscles’ as he put it. He’d always come home desperate for a shower after all of the strenuous activities that made him all hot and sweaty. And even when he  _was_ home, it meant he was spending time with you… which, one way or another, meant you’d end up in the bedroom, giving the poor man yet another workout.

Not that he’d complain, Papyrus had the libido of a wild dog in heat.

Now, you had him in your bed with you. You’d spent a rather nice evening together, he’d romanced you, wooed you into bed and had kept fast attention on your personal  _needs…_  until he fell asleep, flopped naked on your front. Morning came by and he was still curled around you, snoozing gently at the very late hour of seven am.

“Papyrus,” you whisper, stroking the skull that was resting on your chest. He stirred slightly, shoulders rolling, squeezing and then he fell still again, eyes never opening once.

“…What time is it?” you heard him ask groggily.

“Seven.”

“Wha- oh no!” he croaked, cracking his eyes open to look around. He squinted at the sun streaming in through the thin curtains like it had just called him a foul name. “It doesn’t feel like seven! More like an unseemly one. Like you’ve just woken me up in the middle of the night to lie to me and tell me it’s seven–”

“You can go back to sleep again! I don’t mind, I’m a little sleepy myself… You’ve been working so hard lately, Papyrus.”

“I can’t let myself sleep anymore!” Papyrus announced as he upped and rolled away from you onto his back. He stretched again, wider this time, with his whole body. His ribs expanded as he took a large breath and then, all at once, he settled again, eyes lidding like he was ready to fall back asleep.

Something amusing caught your eye then and you chuckled. “You might not be very awake but… someone else certainly is,” you said as you nodded towards the very suspicious tenting that was happening underneath the covers where Papyrus’ crotch would be.

You expected Papyrus to be embarrassed but he merely sighed good-humouredly, giving you a playful grin. “He’s always awake!”

Caught off-guard by his comment, you laugh, making a mental note to catch Papyrus when he was sleepy more often. “It certainly seems that way…” You draw yourself up next to him once again and kiss his jaw. “Would you like me to take care of that for you?”

You could see the cogs in Papyrus’ mind spinning as he contemplated this. The poor skeleton was exhausted but he could never pass up that kind of offer… it just wasn’t in his nature. After a moment’s thought, he rolled onto his side, pulled you into his embrace and began nuzzling at your lips with his teeth to pull a kiss or two from you.

“I can take care of it myself, actually!” Papyrus told you, and with that, you felt his erection pushing up against your clothed thigh, rubbing on it to gain stimulation.

“Naughty!” You began to chuckle at him but were cut off by him tackling you with more kisses. Caught up in his sudden motivation to fool around with you, he rolled on top, somehow making his way in between your legs.

“That feels good,” Papyrus moaned as he thrust the underside of his erection against your crotch. You felt it grow harder against you, his arousal building the more he moved.

“You know what would feel better?” you asked, your own excitement growing as you held the horny skeleton in your arms. “If you let me take my PJs off.”

“Oh wow, you’re always so right,” Papyrus enthused, shifting quickly so he could shuffle your pyjama bottoms off and then your underwear. He flung them over his shoulder dismissively and returned to rubbing himself against you.

It wasn’t long until he was slick from your wetness which made the both of you moan. You could feel his lethargy in every shuddering wiggle of his hips but his eagerness to feel good overrode it. If there was something Papyrus was good at, it was finding little bursts of stamina in an emergency.

And you knew he’d definitely call this an emergency.

“You feel so g-good, y/n,” he groaned.

“Speak for yourself,” you returned. His cock had found a rather nice rhythm running over your clit again and again, making you twitch each time it hit. You were sure he was doing it on purpose just to make you squirm.

His tiredness on that morning only made his actions more languid, the strokes of his cock were slow and deliberate. Teasing. You could barely help wiggling your hips every time you felt his impressive length grind up against you, just aching for him to carry on. Of all the ways you expected your morning to start, this wasn’t one of them. Though you supposed you should hardly be surprised, Papyrus liked to whip his cock out at every chance he got.

He carried on his exceptional behaviour for a pleasurable few minutes until he gasped, ground down harder on the wetness between your legs and began whimpering. All you could do is hold onto him, shivering as he slid against your sensitive opening faster and faster, huffing in your ear with a warm breath until he grunted and slowed completely. You felt his warm cum drip down your entrance and sighed, happy he was satisfied. He fell down by your side then, now well and truly exhausted.

Without any more argument, he snuggled into your side and closed his eyes, giving into the comforting fog that clouded his sleepy mind. Like you had that morning, you returned to stroking his softly-shining skull, lulling him back to sleep.

“Don’t think I’ve forgotten about you,” he murmured, barely audible, “Just you wait until I’m…” he paused to yawn and then settled again. “Rested.”

You kissed the top of his head.

“Oh, I’ll be waiting~”


	3. Mettaton x Reader - Drunk Sex, Messy Sex, Overstim

“Is it just me or is it _hot_ in here?”

“Mettaton, we’re outside. It’s freezing.”

Mettaton, the A-list celebrity, connoisseur of all things fancy, aficionado of the higher class world, was currently wobbling down the street after having far too many glasses of wine, slurring his words and acting like he was perfectly sober.

Not that you could say much, you weren’t exactly sober yourself. A date gone by perfectly in your opinion.

“Well I think things are really... _heating up_.” He winked at you sloppily. Or you supposed it was a wink. His other eye was covered by his long locks of hair yet you were almost sure he’d closed that one too.

“What are you talking about, Mettaton?” you asked, chuckling at what a dork he became when he was like this. Had you been less tipsy, you’d have picked up on his flirtatious remarks much sooner. It’s not like they were particularly difficult to crack.

“I’m talking about... I want to...” He stopped and hooked his chin with his forefinger, thinking deeply, “Ah! Yes, that was it- I want to make out with you in that sketchy little alleyway down there.”

In that moment, that seemed like the most romantic proposal anyone had ever offered you.

It was mere seconds before he had you against a mildly damp wall behind a large dumpster, sheltering the two of you from prying eyes. That is, as long as no one else thought to wander down the alleyway at this ungodly hour also.

Mettaton’s lips were quickly pressed against yours, wasting no time in parting them and slipping his tongue in. _God he really is feeling heated,_ you noted as he kissed you with an urgency that made your head spin. You could feel his lipstick smearing against your mouth, making a complete mess of you. Not that you cared; all you cared about then was Mettaton’s tongue that was sliding against your own.

His hands weren’t shy at all. He ran them over your ass amidst his frantic kisses and decided that’s where they’ll stay. He squeezed it, rolling its plushness around in his palm.

“Y-you were right,” you said as you pulled away from his sloppy kisses.

“Hmm?”

“It really is getting hot in here.”

He chuckled, leaning in for another kiss but you pulled back. “Nuh-uh! I’ve got a better idea of what to do with you.” You swizzled around Mettaton and pushed him against the wall where he moaned at the sudden impact, obviously already beyond lust. You slipped down and onto your knees, not even noticing the hardness of concrete under you for all the alcohol in your system; it seemed you were both currently immune to all usual mood-killers.

It took a few seconds of fiddling around with Mettaton’s belt and zip, but his cock was soon unleashed and half-way enveloped in your mouth. He groaned, hardening from within the wet confines of your mouth, and slipped a hand gently around to the nape of your neck, encouraging you to continue.

“O-oh darling, you are rather _dirty_ , aren’t you?” he slurred. Words were hard to put together when being pleasured and inebriated. “Sucking me off... i-in some grotty little alley.”

You looked up at him through lidded eyes as you bobbed your head on his cock, only able to hum in agreement with his words. You watched as his eyes rolled back in his head as you did so, cutting his teasing short. He was unravelling, you could tell, barely able to stand as his hard cock was being sucked on so diligently.

You thought he was being helpful when he slipped his hand into your hair, pushing it back from your face, when you realised he was simply holding onto your head to make rocking his hips into it easier. It was only a matter of time before the control had switched places and he was the one fucking your mouth, huffing with each thrust of his pelvis. All you could do is hold onto his hips and enjoy the feeling of his cock push into you again and again.

He was close, evidentially. You could tell by the way his moans rose in pitch and by the way his rhythm sped up. He was chasing an orgasm like a hound after a rabbit; with nothing but desperation and a magnificent show of stamina.

“I’m close,” he whined. _Well duh_ , you thought as he pushed on. His orgasm seemed to take him by more surprise than you, and when it came, he pulled out so suddenly that his excessive cum shot onto your lower face and dripped down your chin. He looked down at you with his jaw agape and his chest heaving, completely winded.

That look was so completely erotic that it posed to you an idea that you thought was the best idea you’d ever thought up in that moment. During your relationship with Mettaton, you’d come to learn many things about how he worked, not the least of which was the way his erection could be maintained for as long as it received stimulation. Very useful when you wanted to keep going if he got overly excited too early...

Now, you looked up at him, lips still mere inches away from his cock. He looked back and seemed to have guessed your thoughts, encouraging you with his intense eyes, alight with desire. You made your mind up at once and stood, pulling the robot into a messy kiss whilst you felt him tug your pants down to around your ankles. Now you really were in trouble if anyone decided to walk past.

Mettaton broke the kiss and got you against the wall, face first, laying his lips instead on your neck as he played with the entrance between your quivering legs.

“I’m going to fuck you, y/n,” he whispered loudly in your ear, and then he leant in to mumble, “God, I’m going to be sensitive.”

You braced yourself against the wall with your hands as he pushed inside you from behind, stretching you wide with his hands on your hips. He whimpered immediately, obviously tender from his recent release, too aroused to care. He grunted and huffed, whining every now and then when he got particularly overstimulated, keeping up a sloppy yet persistent rhythm in his inebriated state.

You closed your eyes and let him take you, feeling nothing but heat despite the cold outdoor air that hit your bare thighs. He never failed to turn you on, even in somewhere as dank and un-romantic as this. His hot breath hit your neck as he carried on, his body shivering with delight as he stimulated himself in you. You could tell it wouldn’t be long before he came again.

You moaned as he started to speed up, fingers digging into the soft flesh of your hips as he did so. It was all a rush of enjoyment, the whole experience being something you’d never pictured being quite so hot and yet here you were, close to the edge already. You were sure that if either of you were sober, this situation would never have happened. _Hurrah for alcohol!_ you celebrated mentally as Mettaton fucked you, harder with every desperate thrust.

“I’m g-going to--” you gasp after a short while, bracing around the cock that was hitting your sweet spot relentlessly.

“Good,” Mettaton hissed into your ear sharply, “Cum now. Cum for me, y/n.”

How could you resist an order like that? After one, two, _three_ thrusts, you came, bracing around Mettaton’s relentless cock as you rode out your orgasm, legs locking, head flopping back, mind a haze. It took you a whole ten seconds for your senses to return and realise that Mettaton was still going, at an ever-increased rate.

You groaned as he kept stimulating you, ever so close himself. He tucked his head in the crook of your neck and you could feel how desperate he was to finish, panting like he was running a marathon, thrusting like his life depended on it.

You shivered and whined as he carried on until, at long last, he sighed in great relief and came inside you. His thrusts slowed and he moaned long, drawn-out moans that came from somewhere deep and carnal. His orgasm seemed to last a lifetime and then, as the effects wore off, he pulled out and zipped himself up. You did the same, not caring about the feeling of Mettaton’s cum between your legs, actually starting to feel cold.

He saw you rub your hands together in an attempt to warm up and he pulled you into a tight hug. His body, being an actual working machine, was always warm and cosy, so you leant into him, feeling all fuzzy and warm.

“Shall I carry on walking you home, darling?”

“Do you remember where my home is?”

“Darling...” he paused for a while, and you looked up at him, confusion etched in your features. “At this point, I’m not sure I remember where _my_ home is.”


End file.
